The current solar cycle, cycle 24, was slow to start but in 2011 a rapid rise in the sunspot number occurred which brought about more solar activity. To facilate finding solar flares that have been observed by the partial-Sun EIS observations, an EIS flare catalogue was established in February 2011

Coronal mass ejections are eruptions of plasma and magnetic field from low in the Sun's atmosphere. They act as a valve to release magnetic energy from the Sun's atmosphere and are the major driver of space weather events. Theoretical and observational developments

2011 saw a dramatic upturn in the sunspot number with a corresponding increase in solar flare activity. This included the first X-class flare of the current solar cycle (cycle 24) which occurred on 15 February 2011. As of the time of writing, a total of eight X-class flares

Light-bridges are bright lanes of material that divide the umbra. They are often observed during the break-up of sunspots and therefore can represent the re-establishment of convection. Their increased brightness suggests a higher temperature

This month's nugget celebrates five years of observations with the Extreme Ultraviolet Spectrometer (EIS) onboard Hinode. On October 28th 2006, EIS made its first observations of the solar corona, marking the start of a new era in solar spectroscopy.

Nonlinear force-free field (NLFFF) extrapolation was used to investigate the structure of the field at the time of the main emergence. Here, the extrapolation is based on an SOT/SP vector magnetogram obtained from the scan on 4 July 11:58-12:34 UT.

Evidence of a Connection Between Active Region Outflows and the Solar Wind

(by David H. Brooks, George Mason University and Harry P. Warren, Naval Research Laboratory)

Hinode has revealed the presence of high temperature (few MK) outflows at the edges of many active regions. These outflows show velocities of tens of km/s and appear to persist for at least several days

The Hinode and STEREO satellites are now revealing, in unprecedented detail, one of the phenomena hidden from our view since the loss of the Yohkoh satellite: EUV/X-ray jets or jet-like events from coronal bright points

Determining the source of a magnetic cloud using a velocity difference method

(by Louise Harra, UCL-Mullard Space Science Laboratory)

For large eruptions on the Sun, it is often a problem that the core dimming region cannot be observed due to the bright emission from the flare itself. However, spectroscopic data can provide the missing information through the measurement of Doppler velocities

Sensitivity performance of the Extreme-ultraviolet Imaging Spectrometer (EIS) on Hinode

(by George Doschek, NRL SSD Code 7670)

Scientists in the Space Science Division (SSD) of the Naval Research Laboratory have been studying the sensitivity of the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Japanese Hinode spacecraft

Some active regions display a forward or reverse S structure when observed in soft X-ray or EUV emission. These regions are monitored for eruptive activity as they have a high likelihood of producing a coronal mass ejection

EUV waves were first observed by the EIT telescope onboard the SOHO satellite. They are best seen in the running difference images as bright fronts followed by an expanding dimming region, which is believed to be strongly related to coronal mass ejections (CMEs)

Usually when we observe a feature on the Sun with EIS, we need to decide 1-3 days in advance what we want to look at. It takes this long because the three Hinode instrument teams need to agree on what to observe

The Sun is the only star whose fine structure can be observed from the Earth. Resolving the structure and dynamics of the solar corona is crucial for understanding energy release processes such as flares. Due to this, the resolution of solar telescopes

Response of the corona to the emergence of "serpentine" magnetic field

(by Louise Harra, UCL-Mullard Space Science Laboratory)

New flux emergence into a pre-existing active region clearly can have dramatic consequences, often producing flaring with hours of the flux appearing. The high resolution of the SOT data also shows the complexity of the flux as it emerges with the complex and small-scale positive/ negative (white/black) features appearing

Chromospheric evaporation is largely accepted to be the process by which solar flares achieve their high temperatures and densities. The standard flare model states that electrons are accelerated at or near a magnetic reconnection site in the corona and then travel along newly reconnected magnetic field lines toward the chromosphere

Coronal hole (CH) boundaries are the interface between a CH, where the field is dominantly "open" to interplanetary space, and the surrounding corona where the magnetic field is mainly closed. While CHs are long established to be a source of the fast solar wind

The EIS flare catalogue was created and is maintained by the EIS team at the Mullard Space Science Laboratory (MSSL). We realize that finding flare events with spectroscopic data is more challenging than simple imaging data (watch Demo Movie)